Two novel VPS33B mutations in a patient with arthrogryposis,renal dysfunction and cholestasis syndrome in China's Mainland

Arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome is a rare genetic disorder and has not been described in China. We present a female infant with neonatal intrahepatic cholestasis from a Chinese family with ARC syndrome. All 23 coding exons and flanking introns of the VPS33B gene were amplified and sequenced using peripheral lymphocyte genomic DNA of the patient and her parents. Genetic testing revealed two novel mutations (c.1033delA and c.1567C>T) in the VPS33B gene. The patient is a compound heterozygote and her parents were heterozygous for each of the mutations.

Two novel mutations in the VPS33B gene in a Chinese patient with arthrogryposis,renal dysfunction and cholestasis syndrome 1:A case report

BACKGROUND The VPS33B(OMIM:608552)gene is located on chromosome 15q26.1.We found a female infant with autosomal recessive arthrogryposis,renal dysfunction and cholestasis syndrome 1(ARCS1)caused by mutation in VPS33B.The child was diagnosed with ARCS1(OMIM:208085)after the whole exome sequencing revealed two heterozygous mutations(c.96+1G>C,c.242delT)in the VPS33B gene.CASE SUMMARY We report a Chinese female infant with neonatal cholestasis disorder,who was eventually diagnosed with ARCS1 by genetic analysis.Genetic testing revealed two new mutations(c.96+1G>C and c.242delT)in VPS33B,which is the causal gene.The patient was compound heterozygous,and her parents were both heterozygous.CONCLUSION This study extends the mutational spectrum of the VPS33B gene to provide a molecular basis for the etiological diagnosis of ARCS1 and for genetic counseling of the family.

ARC syndrome with high GGT cholestasis caused by VPS33B mutations

Arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome (OMIM 208085) is an autosomal recessive disorder that is caused by mutations in 2 interacting genes VPS33B and VIPAS39. Mutations in VPS33B gene account for most cases of ARC. As low or normal gamma-glutamyl transpeptidase (GGT) activity has been described in all patients with ARC syndrome identified so far, ARC syndrome is a possible diagnosis for low GGT cholestasis. Here we describe a Chinese patient with neonatal cholestasis and a high GGT level in three consecutive tests. She had other typical manifestations of ARC syndrome, including arthrogryposis multiplex congenita, renal involvement and ichthyosis. Genetic study of the VPS33B gene further confirmed the diagnosis by identification of compound heterozygosity of two known disease-causing mutations, c.403+2T > A and c.1509-1510insG. The mechanism of high GGT in this patient is unclear. Nevertheless, this case indicates that ARC syndrome cannot be excluded from the differential diagnosis of neonatal cholestasis even if high GGT activity is found.